Cellular immunity assays were applied to the study of B95-8 infection in white-lipped, cotton-topped and common marmosets. The conditions were defined for the lymphocyte stimulation assay in marmosets. It was shown that cellular immunity assays could be performed in marmosets and that a number of antigens at various concentrations for different concentrations of peripheral blood lymphocytes could be evaluated in the study of EBV infection in marmosets.